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April 8, 2011

Welders May Be At Increased Risk For Brain Damage

by Sam Savage

Workers exposed to welding fumes may be at increased risk of damage to the same brain area harmed by Parkinson's disease, according to a new study by researchers at Washington University School of Medicine in St. Louis.

Fumes produced by welding contain manganese, an element that scientists have linked to neurological problems including Parkinson's disease-like symptoms.

"In the United States alone, there are more than 1 million workers who perform welding as a part of their jobs," says Brad Racette, MD, professor of neurology at Washington University School of Medicine. "If further investigation of this potential link between neurotoxic effects and these fumes proves it is valid, it would have a substantial public-health impact for the U.S. workforce and the economy."

The study appears online April 6, 2011, in Neurology, the medical journal of the American Academy of Neurology.

The study involved 20 welders with no symptoms of Parkinson's disease, 20 people with Parkinson's disease who were not welders and 20 people who were not welders and did not have Parkinson's. The welders were recruited from two shipyards and one metal fabrication company, and each had an average of 30,000 hours of lifetime welding exposure.

All participants were given brain PET and MRI scans and motor skills tests. A neurologist who specializes in movement disorders also examined all participants. The welders' average blood manganese levels were found to be two times the upper limits of normal blood manganese levels established in prior studies of general populations.

In one area of the brain, PET scans indicated that welders had an average 11.7 percent reduction in a marker of the chemical dopamine compared to people who did not weld. Dopamine helps nerve cells communicate and is decreased in specific brain regions in people with Parkinson's disease. The welders' motor skills test scores also showed mild movement difficulties that were not as extensive as those found in the early Parkinson's disease patients.

Although the same area of the brain was affected as in Parkinson's disease, the pattern of effects within this area was reversed. Parkinson's disease normally has the greatest impact on the rear of a structure known as the putamen. In the welders, the largest drop in the marker for dopamine occurred in a structure behind the putamen known as the caudate.

"While these changes in the brain may be an early marker of neuron death related to welding exposure, the damage appeared to be different from those of people with full-fledged Parkinson's disease," Racette says. "MRI scans also revealed brain changes in welders that were consistent with manganese deposits in the brain."

Racette and his colleagues plan a larger follow-up study to clarify the potential links between welding and brain damage.